The present invention relates generally to a media transportation apparatus for moving printing media from a first location to a second location. The media transportation apparatus of the present invention permits media of various sizes to be moved without the need for expensive and costly equipment.
Current printing technology utilizes a variety of printing methodologies and assemblies. One such printing system is the so-called “Computer-to-Plate” (CTP) system. Reference may be had to U.S. Pat. No. 6,684,783 to Salvestro (Method for imaging a media sleeve on a computer-to-plate imaging machine); U.S. Pat. Nos. 6,662,723; 6,526,886; 6,523,473; 6,523,472; 6,457,413; all to Loccufier (Computer-to-plate by ink jet); U.S. Pat. Nos. 5,992,324 and 5,738,014; both to Rombult (Method and apparatus for making lithographic printing plates in an automated computer to plate imaging system); and the like. The content of each of the aforementioned patents is hereby incorporated by reference into this specification.
A Computer-to-Plate (CTP) system uses a CTP device to imprint a digital image onto a plate. This plate (i.e. media) is conveyed by a transportation apparatus from the CTP device to a processing device. The processing device develops the plate in preparation for printing.
Existing transportation apparatuses suffer from a number of limitations. Prior art transportation devices cannot easily accommodate plates of various sizes. Existing transporters are also prone to jamming. Generally, there are five types of transportation devices: Single wide belt transporters, Plurality of thin belt devices; Gravity rolling devices; Gripping devices, and Switchable devices.
Single wide belt transporters use a single wide conveyor belt to move the printing media (i.e. plate) from the CTP device to the processor device. Such devices are limited by the width of the belt itself. The transporter is unable to accommodate plates that are wider than the belt. Attempts have been made to use extremely wide belts, but such attempts have caused additional problems. Wider belts are difficult to control and thus require additional controlling mechanisms that add to the equipment costs of such assemblies. For example, additional mechanisms are often needed to ensure the belt properly tracks. Wider belts also require higher tension to prevent such a belt from slipping. These high tension belts, in turn, necessitate the use of costly, high torque motors. This higher tension necessitates the use of a more powerful and more expensive motor to drive the wide belt. Wider belts also increase the frictional force that is applied to the printing plate. This additional frictional force often prematurely pulls the plate from the CTP device before the image can be properly transferred to the plate. Such improper handling results in unacceptable image defects in the plate. Additionally, reconfiguration of the device for use with wider plates is difficult—such a reconfiguration requires replacing a substantial amount of the equipment.
Some transporter devices use a plurality of thin belt devices in an attempt to address the issues caused by the single wide belt transporters. However, such a thin belt design gives rise to other problems. The use of multiple thin belts leaves gaps between the belts. If a plate should have a width such that it falls within such a gap, the plates have been known to become lodged between the belt and the pulley that drives the belt, thus producing a jam. It would therefore be advantageous to provide a device that ensures the end of a plate will not rest in such a gap. Additionally, the more belts that are used, the more difficult it becomes to service such belts.
Gravity rolling transporters use inclined rollers to transport a plate from the CTP device to the processing device. However, the speed a plate travels down the incline is difficult to control and depends upon the weight, and thus the size, of the plate. Larger plates travel down the incline substantially faster than smaller (lighter) plates. Some degree of control can be achieved by altering the angle of the incline, however, such control is minimal. The small plates typically require a very steep angle to be properly transported, thus producing a rapid decent. During such a rapid decent, the plate may not fall to the processing device properly. In such an event, user intervention is required to rectify the situation.
Gripping transporter devices engage a plate at a first location, transport the plate to a second location, and thereafter disengage from the plate. One such gripping transporter is disclosed in U.S. Pat. No. 5,465,955 to Krupica (Method and Apparatus for an External Media Buffer), the content of which is hereby incorporated by reference into this specification. The operating speed of such gripping transports must exactly match the speed of the CTP device to which they are attached, or the media may not be properly transported. Moreover, the complexity of such gripping transporters causes them to have low reliability and increased equipment costs relative to other transporters.
Switchable transporter devices have attempted to address these shortcomings, but none of these devices has proven entirely satisfactory. Switchable devices are reconfigured by the user to permit the transporter to accept a media at a first speed, transport the media at a second speed, and deliver the media at a third speed. Such devices are rather complex, and this complexity often results in processing complications and low reliability. Additionally, such devices require user intervention to reconfigure the device for different speeds. The complex nature of the switchable transporter also results in higher equipment costs. One example of a switchable transporter is disclosed in U.S. Pat. No. 4,835,574 to Ohi (Automatic Photosensitive Material Conveying Apparatus), the contents of which are incorporated by reference into this specification.
The prior art considered of some importance to this application includes U.S. Pat. No. 2,682,208 to Monroe (Carton Converting Machine); U.S. Pat. No. 3,117,333 to Murray (Aperture Card Cleaner); U.S. Pat. No. 3,410,183 to Sarka (Material Processing Method and Apparatus); U.S. Pat. No. 3,935,941 to Keck (Adjustable belt conveyor); U.S. Pat. No. 3,938,674 to Kroeze (Method and apparatus for stacking paperboard blanks); U.S. Pat. No. 4,241,910 to Matsuo (Sheet delivering apparatus); U.S. Pat. No. 4,666,140 to Godlewski (Self-contained serially arranged plural section conveyor); U.S. Pat. No. 4,773,638 to Koutoudis (Deposit drawer for a document processing equipment for the deposit of documents having different sizes); U.S. Pat. No. 4,805,890 to Martin (Sheet stacking machine); U.S. Pat. No. 4,835,574 to Ohi (Automatic photosensitive material conveying apparatus); U.S. Pat. No. 4,930,765 to Russel (Sheet collection mechanism for stacking long and short sheets); U.S. Pat. No. 5,054,760 to Reist (Apparatus for conveying flat products); U.S. Pat. No. 5,087,026 to Wyer (Sheet conveying apparatus for conveying variable length sheets to a stack having a selectively positionable transport roller); U.S. Pat. No. 5,277,297 to Tolson (Controllable length conveyor); U.S. Pat. No. 5,465,955 to Krupica (Method and apparatus for an external media buffer); U.S. Pat. No. 5,529,081 to Kappler (Apparatus for the treatment of board-like articles); U.S. Pat. No. 5,609,335 to Parker (High capacity stacker/separating device); U.S. Pat. No. 5,669,604 to Hansen (System for accelerating and transferring imbricated printed products to a gripping chain); U.S. Pat. No. 5,685,539 to Janatka (Disk transport for paper sheets); U.S. Pat. No. 5,692,745 to Neifert (Belt-driven document accumulator having belt-dampening table and side guides); U.S. Pat. No. 5,915,686 to Neifert (Document accumulator having rotating assemblies for ramp adjustment); U.S. Pat. No. 5,954,473 to Folsom (Readily adjustable cut sheet stacker); and U.S. Pat. No. 6,575,457 to Bakoledis (Variable length sheet feeding mechanism). The content of each of the aforementioned patents is hereby incorporated by reference into this specification.
It is an object of this invention to provide a media transportation apparatus capable of transporting media of various sizes that is an improvement over the prior art devices.
It is an object of this invention to provide an uncomplicated, inexpensive media transportation apparatus capable of receiving a media at a first speed, transporting the media at a second speed, and delivering the media at a third speed, wherein the first, second and third speed are not necessarily synchronized.